Almost all the kinds of I/O that z/OS® XL C/C++ supports use this model.
The only ones that do not are z/OS UNIX file
system, memory file, and Hiperspace™ I/O.
The record model consists of the following:
- A record, which is the unit of data transmitted
to and from a program.
- A block, which is the unit of data transmitted
to and from a device. Each block may contain one or more records.
In the record model of I/O, records and blocks have the following
attributes:
- RECFM
- Specifies the format of the data or how the data is organized
on the physical device.
- LRECL
- Specifies the length of logical records (as opposed to physical
ones). Variable length records include a count field that is normally
not available to the programmer.
- BLKSIZE
- Specifies the length of physical records (blocks on the physical
device).